GARDNER, Mass. - This old mill city built prosperity from the force of its waterways. So there was a legacy of renewable energy when the local electrical utility sought to thrust Gardner into the age of inexhaustible sun power, ahead of everyone.

On a summery evening in June 1985, Massachusetts Electric Co. dispatched three managers, two engineers, and an analyst to demystify photovoltaic power for about 70 mostly working-class locals gathered in a college auditorium.

Panels that convert sunlight into electricity had been powering satellites. Now they could electrify Gardner’s homes, not to mention its library and even the Burger King. They would help the country save oil and coal used by utilities to make electricity.

People listened politely. But what got them excited — and helped launch the first photovoltaics test on a community scale — was a question: How would you like to save up to 40 percent on your electric bills?

Sun-catching panels soon covered rooftops of 30 homes and five other buildings around town. The experiment is still running today, almost 20 years later.

Has solar power worked here? Has it worked around the country? Can it help us get beyond our dependence on fossil fuels?

Yes and no, to all three questions.

The bigger solar picture
Solar electric power, the industry says, has reached as many as 20,000 American rooftops, where it has proved it can supplement electrical grids and trim bills.

But its contribution so far is meager.

Despite technological progress, it hasn’t worked reliably enough or economically enough to expand beyond a small fraction of 1 percent of the country’s power generation.

Paul Maycock, who once ran the federal program in photovoltaics, sees its long-range potential as 15 percent, at best. In other words, in the coming age of whatever-replaces-petroleum, it can help greatly — but even its boosters say it can’t carry the load.

It’s not cause for panic. While still a heavy polluter, the coal industry has made environmental strides and can deliver energy for perhaps another 250 years. Photovoltaics and wind power are forecast as the growth leaders among alternative electricity sources for the next 20 years, but other renewables will certainly generate power, produce heat, and run cars. They include solar and geothermal heat, methane gas from garbage, crop-derived gasoline substitutes, and even older methods like burning wood.

Yet 20 years from now, renewable energy will amount to less than 7 percent of Americans’ fuel, the Department of Energy predicts. The dominant 40 percent share will come from that 20th century standby — can you guess? — petroleum.

“Renewable energy will not solve the problem of increasing energy demand by a booming world population, but it does offer a bridge of hope until a replacement energy source for nonrenewable fossil fuels can be developed,” writes geophysicist Dohn Riley. A paid-for opinion from some oil executive? Not at all. He was commenting as director of the Alternative Energy Institute in Tahoe City, Calif.

The grid and Gardner
Gardner’s solar pioneers discovered the limits of alternative energy the hard way — by trying it.

In theory, photovoltaics is sheer simplicity: When silicon, extracted from sand and superpurified, is struck by sunlight, it gives off electric current. No generators, turbines or toil.

In a real building, unfortunately, the system isn’t so simple.

First, a solar cell’s direct current won’t run a normal household’s appliances. It must be converted to alternating current by a box called an inverter. At sites far from power lines, a battery bank is also needed to store electricity for times when the sun isn’t shining. With acid and hydrogen gas, batteries are heavy, expensive and potentially dangerous.

That’s why in Gardner and most other places, photovoltaics are installed in tandem with the existing power grid. The grid handles the load at most times: when the sun sets, clouds thicken or appliances suck more juice than the solar cells can pump.

When the sun comes out, the solar panels take over and send any surplus into the power line for use in the grid. The electric meter spins backward to credit the contribution.

Gardner, a central Massachusetts city of about 20,000, was eager to trail-blaze this new technology.

Like much of hilly New England, its advantage had long been plentiful water power. With coal and oil dominating hydropower in the 20th century, most of Gardner’s busy furniture mills eventually cranked to a halt. Manufacturing and wealth slipped south and west.

When the solar experiment was proposed, some wondered about the choice of a site in New England, which captures a third less solar energy than the Southwest. Still, backers figured, if it worked here, that would prove its versatility.

Inverter troubles, payback was low
The 4-by-6-foot solar panels started going up in the waning light of autumn 1985. Leon Rice, a supermarket meat cutter, got one of the first systems.

Studying the inverter and gauges splayed on his cellar wall like the controls of a nuclear submarine, he saw that, sure enough, when the sky brightened, red lights blinked to life. The inverter softly hummed.

He looked forward to the savings. And yet as his monthly electric bills arrived, Rice didn’t see much change — perhaps $5 saved in the best months, he says.

About a year into the experiment, the inverter broke down and needed to be replaced. Rice didn’t worry. Massachusetts Electric, which had paid to install the $19,000 system and guaranteed upkeep, fixed the inverter.

But later, as the inverter’s lights again went dark, Rice climbed to his roof to check his 10 panels. Water, he discovered, had wicked inside, where it can corrode the cells.

This time when Rice again called the utility, it seemed reluctant to help. Nothing happened for months, until Rice decided to replace his roof shingles. The utility sent workers who unscrewed the 90-pound panels, eased them down by rope, and piled them against the backyard fence to remount later.

There, beneath a tarp, they waited. A project manager at Massachusetts Electric was hoping to find spares somewhere. Weeks passed.

“So I gave them an ultimatum,” Rice says. “I’ll give you a week. Either they’re outta here, or I’m going to have my son throw them in the rubbish.”

They still hog considerable roof space, though. Compared to coal or petroleum, the sun’s energy is dilute. That means it must be harvested by big collectors.

The inverters are still temperamental, solar advocates acknowledge. They chug along well enough for five or six years, then often conk out.

If Gardner had a solar zealot, it was an affable steelworker named Roger Charest, who was happy to help the country cut down on fossil fuels and generate more of its own energy.

In 1985, a $6,500 liquid-heating solar system on his house roof — a simpler technology — already gave him hot water, thanks to a tax credit. So the free photovoltaics went up on his garage. He had a tall maple tree felled to let in more sunlight.

Tax breaks lured thousands of other Americans to try solar heating and power in those years. But the energy crunch subsided, tax benefits disappeared in the mid-1980s and never fully returned, and electricity stayed cheaper than predicted. Solar power never took off.

“It really did look like something of a breakthrough” about 25 years ago, says Joe Broyles, a New Hampshire state energy planner. “Most of the buzz you saw did not include the cost.”

State of solar nationwide
By industry estimates, up to 20,000 solar electricity units and 100,000 heaters have been installed in the United States — diminutive numbers compared to the country’s 70 million single-family houses. Most solar units are in the sunny West and Southwest. Some can supply half of a home’s electricity.

Photovoltaic production has doubled over the past five years. The federal government has a goal of 1 million rooftop photovoltaic and heating solar systems by 2010. For now, it gives solar tax breaks only to businesses, not homeowners.

For them, systems now cost $12,000 or more for typical homes and can take more than 15 years to pay for themselves. Tapping into a power line on the street can cost as little as $100.

A dozen states, including California and New York, are again trying to help by subsidizing photovoltaic systems. The Massachusetts Renewable Energy Trust Fund says about 200 sites have been approved for subsidies in this state.

In Gardner, which was usually overlooked by tourists en route to the Berkshire Mountains, nearly everyone seemed to enjoy the national visibility the test brought at first. Engineers from Europe, Japan, and Australia came. They ate fries at the photovoltaic Burger King.

Japan, with initially heavy government funding, now has close to 200,000 photovoltaic systems. It is the biggest single force behind a fivefold rise in world production since 1998, as reported by the Solar Energy Industries Association. Germany has more than 100,000 units. India and parts of Africa rely on battery-equipped photovoltaics for power in many remote places.

Project engineers quickly declared the experiment a technical success. It was the economics, even with free systems and upkeep, that proved underwhelming. Average annual electric bill savings were less than $200, one consultant estimated.

With that kind of return, the units needed to operate with virtual perfection for many years. They didn’t — and still can’t.

Massachusetts Electric once hoped to transfer responsibility for the units entirely to the homes, and it is trying again this year to extricate itself from the upkeep. But if the utility stopped caring for the systems, many homeowners say they would get rid of them.

Market deregulation has turned many utilities, including Massachusetts Electric, into distributors with little direct stake in how the electricity is generated. “That’s not really part of our mission at this point,” says Richard Sergel, chairman of parent National Grid USA.

Massachusetts Electric was hoping to interest the state in taking over the project in Gardner, where, so far, only four homes have given back their equipment. Rob Pratt, director of the state’s Renewable Energy Trust, said he’s willing to talk about it.

Rice, the meat cutter, has moved to Maine and given up on photovoltaics. “If your goal is to save money, you’re not going to do it. If your goal is to save fossil fuel, that’s fine — but I’m a working guy,” he says.